Trying to add a custom license to the new Campaign-scheme (following the same construction as in https://github.com/wikimedia/mediawiki-extensions-UploadWizard/blob/master/UploadWizard.config.php ) , results in a
Invalid key "licenses" in "Root node"
message and not allowing to save.
Allowing the "licenses" in "Root mode", would give an opportunity to add more country specific licenses (i.e. PD-Denmark50 - http://commons.wikimedia.org/wiki/Template:PD-Denmark50 ) or put on additional warnings for certain licenses. I currently have no opinion on wither a "locally configured" license of the same name as those in the UploadWizard.config.php should take priority, but it should probably also be considered.
See also this discussion on Commons Village pump:
Version: unspecified
Severity: enhancement